In the design of textile surgical implants, it is often desirable to apply a tensile load to the textile structure. For example, in orthopaedic applications the textile implant may be used to replace a damaged ligament. Ligaments join bones to bones and during movement of the body, a load is applied to the ligaments. To anchor the replacement ligament in place, it may be convenient or desirable to use a screw fixation device to anchor the textile implant to the bone so that the load may be properly transferred across the joint.
With a conventional woven textile, if a screw is pushed through the interstices of the woven structure, any load that is applied to the textile will be concentrated at one part of the weave structure, often on a single weft yarn causing the loaded yarn to move within the woven structure causing the weave to become distorted and the point of fixation on the fabric to change. In order to prevent this structural distortion, a number of methods have been suggested to overcome this difficulty. These methods include the use of staples to straddle a number of warp ends of the fabric so concentrating the load on a greater number or width of weft fibres; grommets have also been used which spread the load, not only across the width of the woven fabric but also extending the load bearing down the length of the fabric. However, this approach still results in some distortion of the woven structure, particularly when spaces are forced in the fabric to pass a grommet through.
It is also known that tubular braided structures are difficult to fix in place using conventional screws. The fibres in such a structure are usually angled at between 30° and 60° from the longitudinal axis of the fabric; this permits distortion which is greater than occurs with woven fabrics (where the weft is at approximately 90° to the warp of the fabric), because less load is taken up by the yarn at an angle to the direction of the load.
It may also be necessary for the textile implant to be secured to soft tissue, such as muscle. It is therefore desirable for the textile implant to be capable of being mechanically secured to soft tissue, for example by suturing whilst being able to transfer tensile loadings to the tissue to which it is secured.
It may also be desirable for the textile implant to be capable of promoting tissue ingrowth in order to enable the implant to be biologically connected to the soft tissue.